The invention relates generally to the transmission and storage of data among a plurality of nodes and more particularly to remote management of distribution and control of data through a hierarchy of nodes.
The emergence of digital television broadcasting systems requires a change in traditional methods of communication and management, both between central distribution sites and remote stations and between remote stations and clients. One aspect of the new systems will concern how data is reliably distributed among these entities, and how storage devices are managed.
Methods for broadcast distribution of data objects are known in the art. U.S. Pat. No. 5,613,065 describes a system for information broadcasting utilizing error check codes to determine if a remote client has received a broadcast without error. U.S. Pat. No. 4,908,828 describes the use of cyclic retransmission and CRC testing of a packetized broadcast. U.S. Pat. No. 5,631,907 utilizes cyclic transmission, block numbering and forward error correction for broadcast file distribution along with point-to-point communications to a particular station if blocks are not received after the last cycle. All of these methods require periodic retransmission of the data objects to ensure reliable reception, at a cost of increased bandwidth.
U.S. Pat. Nos. 5,222,061 and 5,535,229 describe systems that utilize retransmission of incorrectly-received packets based upon requests by the client. These systems operate in point-to-point mode and do not take advantage of the broadcast capability existing for a digital television broadcast system. U.S. Pat. No. 5,619,689 adds the capability of aggregating retransmission requests through hub servers, but operates in a point-to-point message-acknowledgement system.
U.S. Pat. No. 4,868,866 describes a method for broadcasting database updates where the updates are modified by comparing the updated material to a record of what had been previously transmitted. Such a method requires the central distribution site to be aware of the state of data objects at each receiving client.
U.S. Pat. No. 5,666,293 describes a method of downloading software through a broadcast channel, where cyclic transmission of packetized data is used for reliable reception. In the method described therein, the same content is broadcast to all clients and the client is responsible for deciding which data to download.
In all of the systems of the above-referenced patents, the memory local to each device is managed by that device, to hold content which has been transmitted from other devices.
What is needed is a system and method for the distribution of content to, and the management of content in, a hierarchy of storage devices, which allows some or all of the local storage in a device to be managed by other devices in the hierarchy, without requiring the managing device to have detailed information concerning those storage devices. It is, therefore, an object of the present invention to provide the foregoing system and method.
It is another object of the present invention to provide a reliable, low-overhead mechanism to distribute data objects to remote clients through a broadcast mechanism which is predominantly one-way, where each node in the distribution system need only have information about the next step in the chain.
Still another object of the invention is to provide a means for ensuring reliable transmission of data objects by utilizing a return channel mechanism (if one is available) only to request retransmissions when specific data blocks are not delivered completely or are found to contain errors. This return channel mechanism optimally aggregates requests from preceding nodes, and each node need only have information about the nodes immediately connected to it.
Yet another object of the present invention is to provide a system and method for managing data objects on remote clients through a hierarchical distribution in a primarily one-way broadcast system, where the amount of information needed by a node is limited to information regarding the immediately connected nodes, and where the source, and many intermediate nodes, are freed from the requirement of knowing specific details about the storage configuration of the client device, or other details regarding the client, such as identity or address information.
The foregoing and other objects are realized by the present invention which, for a network with a distributed hierarchical broadcast architecture, provides a system and a method for efficiently and reliably distributing data content (including audio, video, and software) and remotely managing the storage of content. Both the distribution and the storage management methods are rule-based, utilizing network resources, and particularly network bandwidth, in an efficient manner. Simple and reliable mechanisms are provided for ensuring both data integrity and a high degree of control over storage utilization.
At each stage throughout the network hierarchy, content is distributed to nodes in the subsequent stage based on rules. The rules may be modified at each stage. Each entity in the hierarchy has detailed information of the storage characteristicand of only the entities in the stage immediately subsequent to it, but may nevertheless distribute content to and, through intermediate entities, manage the storage devices of entities which are any number of stages remote from it.
The client device owner specifies a set of preference information which may be used for local filtering, or which the owning (or other) entity may use to select data which targets the client""s interests. The downloaded data may be presented to the client in the form of an interactive application, video, audio, still image, or other format.